In message <[EMAIL PROTECTED]>, Lawrence D'Oliveiro wrote:
> In message <[EMAIL PROTECTED]>, Steven D'Aprano
> wrote:
>
>> On Sat, 18 Oct 2008 09:16:11 +1300, Lawrence D'Oliveiro wrote:
>>
>>> Data can come in fractional bits. That's how compression works.
>>
>> If you don't believe me, try compressing a single bit and see if you get
>> a "fractional bit".
>
> If both states of the bit are not equally likely, then you do indeed have
> a fractional bit, since
>
> nrbits = (- logbase2(P[bit = 0]) - logbase2(P[bit = 1])) / 2
Oops, sorry, the formula should of course be
nrbits = - P[bit = 0] * logbase2(P[bit = 0])
- P[bit = 1] * logbase2(P[bit = 1])
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